Gas tube radio-frequency switch



May 22, 1951 w. H. FLARI'II'Y 2,553,569

GAS TUBE RADIO FREQUENCY SWITCH Filed Jan. 7, 1949 v 2 Sheets-Sheet l 34 3| I: IO 1 INVEN'TOR.'

WARREN H. FLARITY ATTORNEY -May 22, 1951 w, n' 2,553,569

GAS TUBE RADIO FREQUENCY SWITCH Filed Jan. 7, 1949 2 Sheets-Sheet 2 INVENTOR. WARREN H. FLARITY BY W ATTORNEY Patented May 22, 1951 sr res arser orgies GAS TUBE RADIO-FREQUENCY SWITCH Warren H. Flarity, Washington, E10.

Application January 7, i949, Serial No. 59,764

6 Claims.

(Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) impossible because of the lack of a switch tube capable of being exposed to the high-power energy to be switched without being rendered conductive thereby. It is therefore the general ob- .ject of this invention to provide a gaseous switch tube which is solely responsive to a signal applied to its control element.

The present invention, therefore, is not to be confused with transmit-receive tubes commonly used in radar systems to permit use of one antenna for both transmitting and receiving. Transmit-receive tubes are made conductive by the high-power transmitter pulse with the result that the pulse is directed to the antenna. By

contrast, the tube of the present invention is responsive to a control signal and is not aiiected by the high-power energy to be switched.

While the switch tube of the present invention is suited for application in a great many ways, as will be apparent to those skilled in the art, .the tube is especially useful as a part of a system for high-speed switching of high-power radio-frequency energy. Such a system is described in a copending application Serial No.

69,765, filed January 7, 1949. With this-system it is possible to switch a source of high-power radiofrequency energy from one load to another in a fraction-of a microsecond. The switching is perswitch tube will be apparent to those skilled in the art from a perusal of the following description taken in conjunction with the appended drawings of one embodiment of the invention. In the drawings:

Fig. 1 is a sectional view taken longitudinally through a tube constructed in accordance with the teaching of this invention.

Fig. 2 is a transverse sectional view of the same taken on the line 2-2 of Fig. 1.

Fig. 3 is another transverse sectional view of the same taken on the line 3-3 of Fig. 1.

Referring now in greater detail to the drawings, a metallic disk It is made of an alloy such as Kovar which is adapted for forming a glass-tmetal seal. The disks Iii, which of course need not be circular in outline, is provided with a centrally disposed aperture ii. A cylindrical grid support l2 of nickel or other suitable material is mounted on the surface l3 of disk H) in coaxial relationship with the aperture 1 i. The extended end of the cylindrical grid support 12 is covered by a wire mesh grid I4. A nickel grid having 40 lines per inch in each direction was found to give good results. The disk In, cylindrical grid support l2 and grid mesh l4 may together be considered as a control element structure.

A vitreous or metallic cylindricalshell *I'! has an annular edge portion I8 sealed to the surface 53 of disk it, the shell H being disposed in substantially a coaxial relationship with the aperture ii in the disk iii. The shell I? includes a support portion l9 having cathode posts 2-0 and 2'! fused therein. An electron emissive cathode '22 is connected by Wire 23 to post 29, and has an internal heater coil connected by wire 24 to post and by wire 25 to post 2i. Flexible leads 26 and 21' connected to posts it and 2! respectively are disposed externally of the shell ll and are adapted for connection to a source of heater voltage. A control voltage for rendering the tube conductive may be applied across the disk It and lead 25. The voltage so applied is effectively across the grid i i and the cathode 22.

A cylindrical anode 30 of Kovar has one end "31 disposed-coaxially in the aperture II and in-the cylindrical grid support l2. Goodresults have been obtained with a grid-to-anode spacing of about T; of an inch. The other end 32 of the anode 3a? is intended for connection to an inner conductor, for example, of a coaxial line. The anode 38 is maintained in position by means of a'vitreous seal 33 fused to the surface 34 of the disk it and around an intermediate portion of the anode 30.

His apparent from the foregoing that the shell H, the seal 33 and the disk i0 cooperate to form an envelope the interior of which is divided into two chambers by the disk I I]. The aperture l l in the disk ,I c provides communication between the two chambers. The interior of the envelope is provided with an inert gas such as argon at a pressure in the order of microns, for example.

The gas pressure used should be as low as possible, but not so low as to appreciably decrease the life of the tube. The tube should have a gas pressure such as to be operated up on the lowpressure leg of the Pascken law curve of breakdown voltage (between the anode and grid) versus gas pressure.

In use, the switch tube is secured to a conduit or chamber for radio-frequency energy. The conduit or chamber may be a coaxial lin a wave those skilled in the art.

guide, a resonant cavity, or the like. The tube may be arranged with the disk It] on the exterior of the conduit or chamber and with the anode 3B and seal 33 extending through an aperture in the conduit or chamber to the interior thereof. -Many possible methods of utilizing the switch tube, as for example in conjunction with a quarter-wave stub, will suggest themselves to In use, the anode 3i! and vitreous seal 33 are exposed to the radiofrequency energy to be switched, but the energy cannot ionize the gas in the envelope by reason of the attenuation through the vitreous seal and the structural relationship of the parts of the tube.

A source of heater voltage is applied to the leads 28 and 21. The switch tube is rendered conductive, with the result that the anode 3G is placed in electrical contact with the disk H3, when .a control voltage is applied across the disk l (grid i i) and lead2 (cathode 22). The control voltage may be in the form of a firing pulse. The tube may be rendered conductive in a fraction of a microsecond after application of a firing signal. When used in conjunction with an appropriate system of conduits or chambers, a highpower pulse of radio-frequency energy having a duration of a few or several microseconds may be split into two parts and each applied to a different load.

While one embodiment of the invention has been shown and described in some detail, it is to be understood that this has been done by way of illustration and not by way of limitation. It is accordingly desired that the appended claims be given a broad interpretation commensurate with the spirit and scope of the invention.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

l. A gaseous switch tube comprising an apertured metallic disk, a vitreous envelope sealed to the fiat surfaces of the disk and forming a chamber on each side of the disk, the aperture in the disk providing communication between the chambers, a cylindrical grid support extending from the disk coaxially with the aperture into one of said chambers, a grid across the extended end of the cylindrical grid support, a cathode in the same chamber, and an anode in the other chamber having a portion disposed coaxially in the aperture in the disk.

2. A switch tube comprising an apertured metallic disk, a cylindrical grid support extending from one side of the disk coaxially with the aperture therein, a grid across the extended end of the grid support, an enclosure-forming shell sealed to the same side of the disk and a cathode in the enclosure, an anode coaxially'disposed in the disk aperture and grid support and extending from the other side of the disk, and a vitreous seal between said other side of the disk and an intermediate portion of the anode.

3. A gaseous switch tube comprising an apertured metallic disc, a gas filled envelope made of a non-conducting material sealed to the flat surfaces of the disc providing a chamber on each side thereof, the aperture in the disc providing communication between the chambers, control grid structure electrically connected to said disc and covering said aperture, a cathode in one of said chambers, and an anode in the other chamber having a portion disposed coaxially in the aperture in the disc.

4. A gaseous switch tube comprising an apertured metallic disc, a gas filled envelope made of a non-conducting material sealed to the flat surfaces of the disc and forming a chamber on each side thereof, the aperture in the disc providing communication between the chambers, control grid structure electrically connected to said disc and covering said aperture, a cathode in one of said chambers, and an anode in the other chamber having a portion disposed in the aperture in the disc.

5. A gaseous switch tube comprising an envelope member forming a first chamber containing gas at low pressure, an aperture in one end of said envelope, a cylindrical grid structure surrounding and located coaxially with said aperture and including a plurality of closely spaced wires closing the end of the cylinder nearest said first chamber, anode coaxially disposed of extending into the open end of said cylindrical grid structure from without said first chamber, a cathode located in said first chamber, sealing means extending between portions of said envelope surrounding and in close proximity to said aperture and an intermediate portion of said anode so that a second low pressure gas filled chamber is formed thereby.

6. A gaseous switch tube comprising an envelope enclosing a volume of gas under low pressure, a cylindrical grid structure including a plurality of closely spaced wires closing one end of the cylinder disposed in and dividing the envelope into two chambers, one of said chambers being substantially smaller than the other, an anode electrode located in said one chamber and extending into the open end of said cylindrical grid structure and in close proximity thereto, a cathode located in said other chamber.

WARREN H. FLARITY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,416,927 Kingdon et a1. Mar. 4, 1947 2,423,426 McCarthy July 1, 1947 2,428,661 Fitzmorris Oct. '7, 1947 

